Desperately trying to debug poor spam scanning performance

[Ben Tisdall]

Hello all.

I am edging slowly towards the tearing my hair out phase...

I cannot seem to diagnose why an MS box due for installation soon is
performing much more poorly than its soon to be predecessor & indeed my
personal MS box running on desktop hardware.

I'll use my personal box (let's call it desky) for comparison purposes here:

BigOne
======

2 x Xeon dual core 3GHz
2G RAM
2 x 15K SCSI
Hardware RAID 1 (Smart Array 5i)
Exim
Caching dns

Linux newacorn 2.6.18-92.1.10.el5 #1 SMP Tue Aug 5 07:41:53 EDT 2008
i686 i686 i386 GNU/Linux
This is CentOS release 5.2 (Final)
This is Perl version 5.008008 (5.8.8)
This is MailScanner version 4.71.10

Desky
=====

Athlon 64 3200
500MB RAM
7.2K SATA HD
Software RAID 1
Exim
Caching dns

Linux jitter 2.6.18-92.1.6.el5 #1 SMP Wed Jun 25 13:49:24 EDT 2008 i686
athlon i386 GNU/Linux
This is CentOS release 5.2 (Final)
This is Perl version 5.008008 (5.8.8)
This is MailScanner version 4.67.6

AND just to add insult to injury for my capabilities as sysadmin, BigOne
is sitting in a dc with good connectivity & Desky is sitting on the end
of an adsl line!

For testing puposes I have BigOne acting as the primary MX for my
personal mail domain & forwarding on to Desky. I can mail myself & tail
the various logs (speed logging enabled of course) to get a feel for how
quickly individual messages are processed.

Both boxes are running dcc, pyzor & razor2, the fw allows established
connections back in, no timeouts. But in any case even with these
disabled the difference remains.

These are some fairly typical (processed) lines of output from the two
boxes (message sent from gmail).

BigOne:

17:42:09 Spam Checks completed at 2523 bytes per second

Desky:

17:42:17 Spam Checks completed at 5672 bytes per second

Often the difference is much greater in Desky's favour.

BigOne is supposed to go into production next week processing 20k per
day, as things stand I'm not sure it'll hold up.

Any pointers very gratefully received!

Best regards,

Ben.

-- 
Ben Tisdall
Linux Systems Administrator | www.photobox.com